root@host# mysql -u root -p password;Enterpassword:***mysql>useRUNOOB;Databasechangedmysql>createtablerunoob_test_tbl->(->runoob_authorvarchar(40)NOTNULL, ->runoob_countINT->);QueryOK,0rowsaffected(0.05sec)mysql>INSERTINTOrunoob_test_tbl(runoob_author,runoob_count)values('RUNOOB',20);mysql>...
greatsql> insert into t1 values(3,null); Query OK, 1 row affected (0.07 sec) greatsql> select * from t1 where t1.c2 not in (select t2.c2 from t2 where t2.c2 is not null); +---+---+ | c1 | c2 | +---+---+ | 2 | b | +---+---+ 1 row in set (0.00 sec) ...
To test for null values in a query, use IS NULL or IS NOT NULL in the WHERE clause. When query results are viewed in SQL Server Management Studio Code editor, null values are shown asNULLin the result set. Null values can be inserted into a column by explicitly stating NULL in an IN...
Query SQL SELECTname, surnameFROMempFORJSONAUTO, INCLUDE_NULL_VALUES Result JSON [{"name":"John","surname":null}, {"name":"Jane","surname":"Doe"}] Learn more about JSON in the SQL Database Engine For a visual introduction to the built-in JSON support...
DROPTABLEIFEXISTSt_sample_null;CREATETABLEt_sample_null(idINT(11)unsignedNOTNULLAUTO_INCREMENTCOMMENT'自增主键',nameVARCHAR(50)NOTNULLCOMMENT'名称',remarkVARCHAR(500)COMMENT'备注',primarykey(id))COMMENT'NULL样例';INSERTINTOt_sample_null(name,remark)VALUES('zhangsan','张三'),('李四',NULL); ...
下面向子查询的t2中插入一条c2列为null的记录。greatsql> insertinto t2 values(,null);再观察一下三条语句的执行结果:greatsql> select * from t1 where t1.c2 notin (select t2.c2 from t2);Empt 结论 使用not in 的非关联子查询注意NULL值对结果集的影响,为避免出现空结果集,需要子查询中查询列加is...
mysql>insertintotest(id , name)values(1,null); Query OK,1rowaffected (0.01sec) mysql>insertintotest(id , name)values(2,''); Query OK,1rowaffected (0.01sec) mysql>insertintotest(id , name)values(3,' '); Query OK,1rowaffected (0.00sec) ...
obclient> CREATE TABLE t_null(id NUMBER NOT NULL PRIMARY KEY, name VARCHAR(10)); Query OK, 0 rows affected obclient> INSERT INTO t_null(id, name) VALUES(1,'A'), (2,NULL), (3,'NULL'); Query OK, 3 rows affected Records: 3 Duplicates: 0 Warnings: 0 obclient> SELECT id, name...
SQL> insertinto emp(empno,ename) values(8888,'Dave'); 1 row created. SQL>commit; Commitcomplete. 这里我们只插入了empno和ename,其他为空。 下面进行2张表的的操作: SQL> selectempno,ename from emp where job not in (select job from emp1); ...
ageIN(SELECTageFROMVALUES(50), (null) sub(age)); name age--- ---Fred 50 Dan 50-- Since subquery has `NULL` value in the result set, the `NOT IN`-- predicate would return UNKNOWN. Hence, no rows are-- qualified for this query.>SELECT*FROMpersonWHEREageNOTIN(SELECTageFROMVALUES(...